Method for monitoring objects or an object area

ABSTRACT

A laser-based target detection system applicable to search and rescue operations takes into account a plurality of optical attributes in the energy delivered to, and received from, a target-containing area. In addition to analyzing the returned optical signature for sufficient energy reflected by a potential target at a primary laser wavelength, the system also senses the target&#39;s effect on a supplemental optical attribute. Only when sufficient amplitude at the primary wavelength is detected in conjunction with a substantial effect on the supplemental optical attribute is a valid target confirmed. The supplemental optical attribute can be amplitude at a wavelength other than the primary wavelength, with the system looking for a high degree of attenuation at the non-primary wavelength, or polarization. with the system preferably looking for change of orientation in the return optical signature. The system includes scan head chassis ( 102 ) for transmitting energy to a target-containing area, electronic chassis ( 104 ) for processing the received optical energy, laser pulse drive ( 106 ), and laser cooler ( 108 ).

FIELD AND BACKGROUND OF THE INVENTION

The invention relates to a method for monitoring objects or an objectarea. An optoelectronic rangefinder has been provided which comprises atransmission device for transmitting optical signals which latter termshould be understood in the broadest sense as an electromagneticradiation either in the visible or invisible range. This rangefinderdetermines values of distance either from pulse timing (in a more narrowsense) or the phase relationship (Doppler system) of the transmittedoptical signal, thus being a pulse timing rangefinder in the broadersense.

SUMMARY OF THE INVENTION

With such a method, it is an object of the present invention to enlargeand to improve its applicability in various practical fields. Such amethod in accordance with the invetion is especially suited for fieldsof use, such as recording a scene of an accident or the surrounding of acriminal deed, but also for surveying objects or object spaces. Afurther field of use is recording cultural assets, such a buildings, orchanges of an environment. The further values, which are assigned to thedistance values, may be values of amplitude or passive image signalsobtained from a beam splitter postponed to the scanner, or measuringvalues of an earlier measurement which values are combined with theactual measuring values, particularly in order to be able to discernchanges of range-finder images (e.g. over time).

Just in the latter field, there will be very little change over timewhich is difficult to discern. The same difficulty in discerning resultsfrom movements of structures which cannot be detected visually oroptically due to their contrast which is little or absent at all, as forexample snow fields or scree slopes, but also in badly illuminated roomsto be surveyed. The invention with features thereof overcomes thesespecial problems. A combination can be an additive or multiplicative oneor the like, but suitably is effected by forming the difference.

The subject matter of this embodiment of the invention is to be seen inthat after first scanning the object range and evaluating its data, theyare stored in a memory as a reference set of data, and the sets of dataof subsequent scannings are combined with the reference set of data, adifferential set of data preferably being superimposed to the referenceset of data or to the actual set of data, particularly in coded form,and are displayed and put out as an image on a monitor. Such a methodmay be used in alarm systems, on the one hand, and may serve theprotection against burglary or other unauthorized intrusion or fordiscovering assassination attempts by deposing explosives. On the otherhand, this method is able to visualize changes which develop at veryslow rates, such as slides of mountain slopes or waste dumps as well assettlement phenomena in a terrain.

Applying this embodiment of the method according to the invention inalarm installations has the advantage over the well-known use of videosystems that illumination of the object or object space is not necessaryso that the fact of the surveillance cannot be recognized by anintruder. Moreover, the method according to the invention is insensitiveto a large extent against attempts of deceiving or manipulating it,because it does not compare the structure of a surface, but ratherthree-dimensional images.

Certainly, known devices using a method of the above-identified typeproduce a so-called distance image on the screen of a monitor whichindicates the respective distances from the surveying unit by mockcolors. Such a distance image is a very suitable representation in manyapplications giving a good overview of objects distributed in depth. Ofcourse, ouch distance image cannot or not clearly resolve structureswhich do not have any spatial depth at all or only a small one. For thisreason, the method according to the prior art could not be applied forsaving evidence after traffic accidents, because important elements ofevidence, such as skid marks, splinters and other smaller parts of a caras well as marks applied by an officer to the road could not bedissolved in the distance image. Therefore, the situation after atraffic accident is usually still measured manually, e.g. by aperambulator, and is photographically recorded.

It has also been suggested to carry out measurements of an accidentsituation by means of a laser rangefinder first measuring points from aposition the localities of which are indicated in maps or road maps,e.g. of buildings, traffic signs and so on, and then the cars involvedin the accident and other objects relevant for the accident event. Ifwith this method or with the purely manual one or other measurement hasnot been made, it is generally difficult, or even impossible, todetermine precisely the position of certain objects afterwards.

A further disadvantage of the two methods described above is that theyare extremely time consuming so that the place of an accident is blockedfor a long period, thus resulting in severe traffic jams. All thesespecial problems are solved in a simple manner by features of theinvention.

Due to shading by individual objects in the space to be taken, a singlerecording cannot, in general, provide a complete three-dimensionalinformation of this space. Therefore, at least two recordings arepreferably made of substantially the same space from different angles ofview. When subsequently evaluating the image, several identical pointsin the different images are marked so that an electronic calculator cangenerate a complete set of three-dimensional data upon the followingimage processing from the data of the different images. Thus, it ispossible upon later evaluation to show pictures of the scene taken underany angle of view desired on a screen or print, and in particular it ispossible to output a bird's-eye view, a perspective or a parallelprojection so that the evaluating officer obtains automatically arepresentation of the recorded space similar to an aerial photograph.Since the space coordinates to each point of the recorded space exist asa reference in the set of three-dimensional data, important imageelements can be marked, e.g. by a cursor on a computer screen, inaddition to a graphical display, optionally in correct scale, and thespace coordinates of a point and/or the distance to any other markedpoint can be issued.

According to this variant of the method, generally two or threerecordings are made of a place of accident. Immediately after recordingand, optionally, a first control of data, the place of accident can becleared and clearance be given for the traffic, because all sorts ofevaluations and measurements can be carried from the recorded data outlater.

An apparatus for carrying out the method according to the invention asprovided. Using one or more high sensitive photoreceivers, it ispossible to record a the scene of an accident or the like even indarkness without any expensive illumination.

BRIEF DESCRIPTION OF THE DRAWINGS

Further characteristics of the invention will become apparent from thevarious subclaims and the description of an embodiment making referenceto the figures of the drawings in which:

FIG. 1 shows schematically, partly as a block diagram, an apparatusaccording to the invention;

FIG. 2 by way of example, an image generated by the novel apparatus; and

FIG. 3 is a block diagram showing further functions of the apparatus ofFIG. 1.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

The apparatus according to FIG. 1 comprises an active optical channel 1which consists substantially of a laser range-finder. The active channelcomprises a transmitter diode 2 as well as a receiver diode 3. By thetransmitter diode, a sequence of extremely short laser pulses aretransmitted which are reflected by objects located in the target area.The beam reflected towards the recording apparatus is received by thereceiver diode 3. From the transit time or the phase relationship of thelaser pulses, the distance to the respective object is determined withinthe laser rangefinder or the active channel 1. An optical scanningsystem is mounted up-stream of each of the transmitter diode 2 and thereceiver diode 3. For the sake of a clear representation, only thescanning device for the receiver diode 3 is illustrated and described asfollows.

A beam 4 impinging on the receiver diode 3 over an optical axis of thesame reference numeral is deflected, for example, by a sweeping mirror 5driven by an actor 6. An angle sensor 7, that is connected to the actor6, outputs a signal σ which depends on the position of the mirror 5. Thebeam 8 transmitted by the sweeping mirror 4 impinges on a mirror surfaceof a mirror prism 9 along the optical axis 8 which is driven at a highspeed by a motor 10. The respective angular position of the mirror prism9 is measured by a sensor 11; corresponding signals φ are fed to asignal processing stage 12. By moving the mirror 4 and the prism 9, theobject space is linearly scanned by a beam 13 along a further opticalaxis.

The scanning arrangement for the transmitter diode is constructedanalogously and scans the object space synchronously and with the samephase relationship in both directions so that the beam 13 and thecorresponding beam of the transmitter arrangement are substantiallyparallel. Advantageously, the two movable optical elements 4 and 9 forthe transmitter channel and the receiver channel use the same drivingelements 6 and 10. It may be convenient to extend the mirror 4 and theprism 9 in axial direction so that the transmitter channel and thereceiver channel may even make use of the same transmission devices.According to another embodiment of the invention, the laser rangefinderincluding its transmitter optics and receiver optics together with therotating mirror prism could be combined to a fixed unit which is pivotedas a whole for scanning the object space.

By the active channel 1 (laser rangefinder) in combination with thescanning arrangement, the object space is scanned, a distance valuebeing determined in conjunction with each space direction defined by thevalues of the angle sensors 7 and 11. The corresponding set of data,consisting of the image coordinates and the assigned distance value, isfed to a signal processing or evaluation stage 12, which is formed as aprocessor or calculator and, suitably, is provided with assignedmemories, which generates a so-called distance image from the data, thatis displayed on a monitor 18, by a printer (e.g. a color printer) or byany other image producing device. The distance image can be issuedeither in gray tints or in mock colors, a gray scale or a color scalebeing assigned to a distance scale. In addition, the distance of animage element or its space coordinates can be displayed directly byclicking it on.

In addition to the distance image, an amplitude image can be obtainedfrom the active channel in which the amplitude of the reflected laserpulses received by the receiver arrangement is assigned to each imageelement, independently of its distance value. Since such an image showsstructures in surfaces of the same distance, the evaluation of theimages is substantially simpler, above all if an distance image issuperimposed to an amplitude image.

Still more favorable is it if the object space, concurrently with theactive channel, is scanned for a passive channel. Such an apparatus isillustrated in the drawings and is described in detail as follows:

A beam divider prism 14 is arranged within the path of rays of the beam4 between the sweeping mirror 5 and the receiver diode 3, the beamdivider prism providing part of the incident radiation to a secondphotodiode 15. Advantageously, the photodiode 15 has a differentspectral sensitivity as compared with the diode 3 the spectralsensitivity of which is adapted to the transmitter diode 2. It may besuitable to use one diode for a long-wave infrared in order to achievebetter penetration of fog. For other applications, a photodiode for thevisible spectral range may be used. Instead of a single photodiode, atriple of photodiodes being sensitive for the three basic colors may beused. The spectral sensitivity may be adjusted by color filters (such asa color filter 15A shown in phantom) or dichroic mirrors mountedupstream, as known per se. Advantageously, the beam divider prism(splitter) 14 too has a dichroic mirror surface 16 through which theradiation of the laser diode 2 can pass substantially unimpeded, whileradiation for which the diode 15 shows a maximum sensitivity isoptimally reflected.

In order to be able to employ sech an apparatus also in darkness withoutany additional illumination, an image amplifier 15B (indicated inphantom), as is known per se, may be situated upstream, or a photoreceiver of high sensitivity may be used instead of a photodiode, as isthe case in the present embodiment.

The signals derived from the photodiode 15 or the respectivephotoreceiver, as a whole, describe a passive image of the object spacewhich is congruent with the distance image, but, in terms ofillumination, is independent of the laser light of the transmitterdiode.

The signals are processed in the stage 17, called “passive channel” andare supplied to the signal processing stage 12 in which now not only adistance information exists, but also a luminance information andoptionally a chrominance information assigned to each point which isdefined by the sensors 7 and 11. These latter informations are firststored in memories of the stage 12. Then the data are further processedin the stage 12.

The output signals of the signal and data processing stage are suppliedto a control and display unit 19 and 18. The data both of the activechannel and the passive channel can be displayed as an image, optionallyin a mock color technique, preferably superimposed on a monitor. Byappropriate commands, certain distance images or sequences of distanceimages can be selected and stored in a reference data memory 20. Thedata of a distance image stored in the reference memory 20 are combinedwith actual distance image data, i.e. subtracted or superimposed, in adata processing stage 21 and are then switched through by the controlunit 19.

In the present embodiment, a differential image is produced containingonly those image elements the position and/or distance of which haschanged in comparison with the reference image. In order to be able tofacilitate assigning this differential image to the object space, it isrecommended to superimpose it preferably to the reference distance imageor to an assigned amplitude image or to a reference image derived fromthe passive channel. The differential image is preferably coded, e.g. inmock colors, and is superimposed to a gray scale reference image. In anadvantageous manner, mock color coding is effected so that anapproaching object, with increasing change of distance, is shown in anintensifying red, with an enlarging distance, however, in anintensifying blue. The manner of coding the differential image andsuperimposing it over a further image to be defined can be determined bythe control unit 19 which controls the stage 21 accordingly.

The mode of operation of this embodiment of the method according to theinvention is discussed in detail as follows:

When the installation has been made operative, a distance image is firstproduced by the laser rangefinder scanner and is displayed on themonitor 18. By the control unit 19, any desired reference image may bedefined and stored in the memory 20. Further parameters, such asscanning frequency, threshold values for the automatic surveillance ofthe differential images and so on, may be defined by the control unit.It is also possible to actualize the reference image automatically so asto cut deliberately any slow change out of the display. In operation,the actual set of data supplied by the laser rangefinder scanner iscompared with the set of data stored in the memory 20. The differentialset of data, thus produced, is either displayed on a monitor as an imageand/or is processed by the control unit 19 to a characteristic magnitudeusing a defined algorithm. The latter is compared with a boundary valueto be defined. Upon exceeding the boundary value, an alarm isautomatically released. In this way, it is possible to operate such aninstallation even without any human assistance.

When applied in security systems, the particular advantage of thismethod resides in that it is very flexible, on the one hand: for, uponstirring the alarm installation up, the object space is recorded by thelaser rangefinder scanner, and this image is stored as a reference. Eachchange of this spatial image is either displayed or releases an alarm.On the other hand, the system is totally insensitive against changingconditions of the environment, such as conditions of illumination, and,above all, it is safe against any attempt of deceit, camouflage and soon, because an intruder dressed in black, for example, is visually notperceptible in front of a black background, but very well in a distanceimage, because he changes the three-dimensional structure of the objectspace.

However, the system is suited also for surveying objects which showhardly any contrast or lack contrast at all, such as a snowy or screefield, an avalanche stretch or a mudflow stretch and so on. It is anadvantage of this system that it is also suited to detect very slowlydeveloping changes, such as sliding terrain and settlement phenomena inwhich changing illumination conditions and vegetation, generally, doalso not affect the measurement results.

FIG. 2, by way of example, represents a monitor image 20′ of an accidentscene as a further embodiment. When “clicking” a first object 21′ on,the spatial coordinates of this object can be displayed in a coordinatesystem to be defined. If a second point 23 is “clicked on”, in additionto its coordinates 24, the distance from point 21′ and, optionally alsoits direction (relative to the coordinate system chosen) can be issuedin addition.

As a rule, at least two recordings are made from one scene in order toobtain a complete three-dimensional data file in spite of inevitableshadings of portions of the scene by various objects positioned in it.In this way, it is advantageously possible to calculate vectors. In afirst evaluation, at least two objects, e.g. traffic signs, masts,building roofs and so on, are marked in the different images as beingidentical. In a further run of image evaluation in the signal processingstage 12, the data of different recordings are combined to a singlethree-dimensional data file. Optionally, the set of differential datacan be examined using given algorithms, e.g. stored in a memory of theevaluation unit 12 (e.g. the least squares method) for reducing thepossibility of mistakes, a signal being released when a defined,preferably selectable, boundary value is exceeded.

When such a three-dimensional file exists, the scene, in a laterevaluation, can be displayed turned at will (FIG. 3 at 37) for makingvarious details visible. It is also possible to generate a plan view,e.g. by turning the vectors by computation, so that a site plan of aplace of accident, preferably according to scale, is displayed on ascreen or may be printed out, the distance of important points beingoptionally indicated in addition.

The invention is not limited to the embodiments described above. Insteadof or in addition to the passive channel as an image information, theamplitude of the reflected laser pulses from the active channel can alsobe used. Since this image information is totally independent of theprevailing illumination conditions, it is preferably used as an imageinformation when a whole scene or part of it is badly illuminated.Optionally the amplitude signals are superimposed to the signals of thepassive channel.

In, order to elucidate the spatial depth of a luminance image still moreclearly, a mock color distance image, known per se, can be superimposedto it, according to a further characteristic of the invention.

For improving the recording properties of the passive channel indarkness, an illumination source can be arranged either in thetransmitter channel or in the receiver channel. Since the object spaceis also illuminated point-by point by the scanning arrangement, a verysmall power of the illumination source would be sufficient in this case.

If, upon recording, a considerably reflecting object, e.g. a wind screenor a puddle is aimed at, the surface normal of which including a more orless large angle, the receiver arrangement of the rangefinder will notreceive any signal from such an object. Thus, a distance value from thisobject is missing. Such missing distance values can be determined by aninterpolation procedure (FIG. 3 at 38) in the calculator 12 from thevalues of adjacent image elements so that even in such exceptional casesa complete set of data can be produced.

The foregoing functions, described with reference to FIG. 1. areexplained further with reference to the diagram of FIG. 3. Input signalsare applied to the signal processing stage 12 from the components 1, 7,11 and 17 set forth in FIG. 1. A further input signal to the signalprocessing stage 12 is provided by a navigation unit 31 having both aGlobal Positioning System (GPS) and a digital compass. The signalprocessing stage 12 evaluates data carried by the input signals at 32 tostore angular coordinates of each of numerous points of an image in amemory 33. The data evaluation also results In image point informationincluding luminance, chrominance and distance, indicated at 34. Thedistance and coordinates are employed to provide a three-dimensionaldata file at 35. The distance is also applied to a coding section 36 ofthe processing stage 12 to output signals which command the monitor 18(FIG. 1) to present a mock color or gray scale to indicate range of apoint in a displayed image.

In the control unit 19, there is provision for generation of adifferential image from the data of two images, for determination ofboundary values, or thresholds, between signal amplitudes, such as fordetermining suitable values of distance at which mock colors areestablished. Also, a routine for establishing a presentation of slowlychanging phenomena, described above, is performed in the control unit19. Operation of the control unit 19 employs information obtained fromthe signal processing stage 12. The data proceeding stage 21 providesthe functions of combining images and of superimposing images, as shownin FIG. 3, with images being stored in the reference memory 20. Theprocessing stage 21 and the memory 20 are connected to each other andthe control unit 19 to provide for communication of data among thesecomponents.

Moreover, in addition to the applications mentioned above, the inventionmay generally be used for various measuring tasks, e.g. in constructionengineering or in mechanical engineering. It may be used for controllingautonomous vehicles as well as a sensor in robotic systems. Mainly whenused for measuring tasks in construction engineering it may berecommended to combine the installation with a navigation system, e.g. aGPS satellite navigation system, GPS, so that the coordinates of thedifferent image points can be issued as geographical or GPS coordinates.

What is claimed is:
 1. A method for recording an image of a target areausing an optoelectronic rangefinder and a passive imaging device,wherein the rangefinder comprises: transmission means for transmittingoptical signals along a transmission axis, receiving means for receivingoptical signals reflected by objects located in said target area intime-shifted relationship relative to said optical signals of thetransmission means and along a receiving axis substantially parallel tosaid transmission axis, optical means mounted upstream of both saidtransmission means and said receiving means, and providing that thereceiving axis is substantially parallel to the transmission axis, theoptical means including scanning means for deflecting optical axes ofsaid transmission means and said receiving means in different directionsacross said target area to obtain coordinates of points of the image,said optical means serving to provide a first spectral bandwidth totransmitted and received optical signals of said rangefinder, whereinthe passive imaging device views said target area via said scanningmeans, said optical means providing said passive imaging device with asecond spectral bandwidth; wherein the method comprises steps ofevaluating data obtained by said rangefinder based on information fromsaid scanning means for determining distance values of the objects inthe target area from said time-shifted relationship to provide signalsrepresenting distances of the points in the image, and reproducingindividual image points according to data obtained by said rangefindervia said first spectral bandwidth and by said passive imaging device viasaid second spectral bandwidth, with the coordinates of said imagepoints corresponding to a deflection of said scanning means, said secondspectral bandwidth being greater than the first spectral bandwidth toimprove clarity and presentation of the image.
 2. Method as claimed inclaim 1, wherein different directions of deflection of a beam by saidscanning means comprise at least two orthogonal directions.
 3. Method asclaimed in claim 1, wherein said image reproducing step employs at leastone monitor.
 4. Method as claimed in claim 1, further comprising thefollowing steps: scanning said target area by said scanning means for afirst time and evaluating signals reflected by the objects in saidtarget area to obtain a first set of said data; storing said first setof data as a set of reference data; scanning said target area by saidscanning means for at least a second time and evaluating signalsreflected by the objects in said target area to obtain at least a secondset of said data; combining said at least second set of data with saidfirst set of data to obtain differential amplitude for points of saidimage; and reproducing a combination of said data of said image pointswith said differential amplitude in the form of a combination image. 5.Method as claimed in claim 4, wherein said step of combining comprisessuperimposing said second set of data to said first set of data. 6.Method as claimed in claim 4, wherein said step of combining comprises aprevious step of coding said data.
 7. Method as claimed in claim 6,wherein said step of coding is effected in the form of mock colors. 8.Method as claimed in claim 7, wherein said step of reproducing comprisesreproduction of an image in color coded form, the color hue representinga function of a distance difference between said first and second setsof data.
 9. Method as claimed in claim 8, wherein said color coded formcomprises mock colors as a code.
 10. Method as claimed in claim 1,further comprising a step of transmitting laser signals by saidrangefinder, wherein said transmission means include laser means fortransmitting laser signals.
 11. Method as claimed in claim 10, whereinsaid laser signals are in the form of pulses.
 12. Method as claimed inclaim 11, further comprising the step of deriving a series of at leastone of received amplitude, luminance and chrominance signals, the lattertwo from a path of rays of at least one of said transmission means andsaid receiving means after said scanning means, to define said imagetherefrom.
 13. Method as claimed in claim 12, wherein said distanceimage signals and signals of said passive imaging device are combined toform a combination image.
 14. Method as claimed in claim 12, furthercomprising the following steps: scanning said target area by saidscanning means for a first time and evaluating signals reflected by theobjects in said target area to obtain a first set of said data; storingsaid first set of data as a set of reference data in a memory means;scanning said target area by said scanning means for at least a secondtime and evaluating signals reflected by the objects in said target areato obtain at least a second set of said data; combining said at leastsecond set of data with said first set of data; and reproducing thecombination of said first and second sets of data in the form of a firstimage; and forming a combination image by superimposing said first andsecond images.
 15. Method as claimed in claim 14, wherein said memorymeans stores signals for a distance image and a second image, therebeing a further step of determining differential images from both saidfirst and said second images to be reproduced.
 16. Method as claimed inclaim 13, further comprising the following steps: determining firstspatial coordinates of a fixed point; determining second spatialcoordinates of different selected image points; setting said first andsecond spatial coordinates into relationship to each other; andreproducing said relationship.
 17. Method as claimed in claim 16,wherein the range finder operates with processing means adapted torotate said spatial coordinates to provide an image seen from adifferent angle.
 18. Method as claimed in claim 1, further comprisingthe step of interpolating a distance value, in case it is missing for animage point, from distance values of adjacent image points serving as areference.
 19. An apparatus for recording an image of a target area,comprising: an optoelectronic rangefinder which includes transmissionmeans for transmitting optical signals along a transmission axis, atleast one receiving means of a predetermined spectral sensitivity forreceiving optical signals reflected by objects located in said targetarea in time-shifted relationship relative to said optical signals ofthe transmission means and along a receiving axis substantially parallelto said transmission axis, optical means mounted upstream of both saidtransmission means and said receiving means to define a path of rays,said optical means including at least one beam splitter for supplyingpart of said reflected optical signals to said at least one receivingmeans; a passive imaging device, and scanning means for deflecting saidoptical axes of said transmission means and said receiving means and anoptical axis of said passive imaging device in various directions,wherein said range finder operates with a first spectral bandwidth toobtain range data of points within the target area, said imaging deviceoperates with a second spectral bandwidth to obtain an image of pointswithin the target area, evaluation means for determining distance valuesfrom said time-shifted relationship to provide the signals of a distanceimage, reproducing means for reproducing individual image pointsaccording to data obtained by said range finder via said first spectralbandwidth and by said passive imaging device via said second spectralbandwidth, the coordinates of said image points corresponding todeflection of said scanning means, said evaluation means serving forsuperposing range data upon the image data for points of the image, saidsecond spectral bandwidth being greater than the first spectralbandwidth to improve clarity and presentation of the image. 20.Apparatus as claimed in claim 19, wherein said transmission meansinclude laser means for transmitting laser signals.
 21. Apparatus asclaimed in claim 19, wherein said various directions of deflectioncomprise two directions orthogonal to each other.
 22. Apparatus asclaimed in claim 19, wherein said image reproducing means comprise atleast one monitor.
 23. Apparatus as claimed in claim 19, furthercomprising color filter means situated between said beam splitter andsaid at least one receiving means for providing a designated spectralsensitivity to said receiving means.
 24. Apparatus as claimed in claim19, further comprising image amplifier means assigned to said receivingmeans for increasing the sensitivity.
 25. Apparatus as claimed in claim19, further comprising compass means connected to said evaluation meansfor defining a coordinate system in relation to a fixed point as areference to said measured distance values.
 26. Apparatus as claimed inclaim 25, wherein said fixed point is the actual position of saidoptoelectronic rangefinder.
 27. Apparatus as claimed in claim 25,wherein said compass means comprise a digital compass.
 28. Apparatus asclaimed in claim 19, further comprising navigation means for determiningthe position of said optoelectronic rangefinder as a reference to saidmeasured distance values.
 29. Apparatus as claimed in claim 28, whereinsaid navigation means comprise a GPS system.
 30. A method for presentingan image of a subject by use of an optoelectronic rangefinder and apassive imaging device, comprising the steps of: providing the rangefinder and the imaging device with a scanner; operating the range finderwith a scanning of the subject by a beam having a first spectralbandwidth to obtain range data of points within the subject; operatingthe passive imaging device with a scanning of the subject in a secondspectral bandwidth to obtain an image with image data of points withinthe subject; superposing range data upon the image data for points ofthe image; and wherein the second spectral bandwidth is greater than thefirst spectral bandwidth to improve clarity and presentation of theimage.
 31. Method as claimed in claim 30, wherein said scanner deflectsoptical axes of said transmission means and said receiving means and anoptical axis of said passive imaging device in different directionsacross said subject, and said different directions of deflectioncomprise at least two orthogonal directions.
 32. Method as claimed inclaim 30, further comprising a step of presenting said image by use ofan image reproducing means comprising at least one monitor.
 33. Methodas claimed in claim 30, including a step of spectrally filtering signalsreceived in an active channel of said range finder from signals receivedin a passive channel of the imaging device.
 34. A method according toclaim 30, wherein the second spectral bandwidth is in the visiblespectrum.
 35. A method according to claim 30, wherein the first spectralbandwidth is in the infrared spectrum.
 36. A method as claimed in claim30, wherein said scanning is accomplished by means of a scanneroptically coupled to said range finder and said passive imaging device,the method further comprising steps of: reproducing individual imagepoints with the coordinates of said image points corresponding to adeflection of said scanner, storing said image points, determining adescriptive parameter from said range data, and assigning thedescriptive parameter to respective ones of the image points, anddescribing the image in terms of descriptive parameters obtained fromdata of both said range finder and said passive imaging device. 37.Method as claimed in claim 36, including a step of spectrally filteringsignals received in an active channel of said range finder from signalsreceived in a passive channel of the imaging device.
 38. A method forpresenting an image of a subject by use of an optoelectronic rangefinderand a passive imaging device, comprising the steps of: providing therange finder and the imaging device with a scanner; operating the rangefinder with a scanning of the subject by a beam having a first spectralbandwidth to obtain range data of points within the subject; operatingthe passive imaging device with a scanning of the subject in a secondspectral bandwidth to obtain an image with image data of points withinthe subject; superposing range data upon the image data for points ofthe image; and wherein the second spectral bandwidth differs from thefirst spectral bandwidth.
 39. A method according to claim 38, whereinthe second spectral bandwidth comprises the infrared spectrum.